In various analytical procedures used to characterize a particular sample, it is often necessary to link the output of a first instrument to the input of a second instrument. For example, it is known to connect the output line of a gas chromatograph to the input of a mass spectrometer to permit analysis by the mass spectrometer of the components of a sample separated by the gas chromatograph. It is also known to directly link equipment which prepares a sample for analysis with the instrument which actually performs the analysis. For example, it is known to link the output line of an auto-sampler device to the input of a gas chromatograph to permit analysis by the gas chromatograph of the multiple samples prepared from vials cycled through the auto-sampler device.
In the case of the auto-sampler device as the first instrument and a gas chromatograph as the second instrument, the output of the auto-sampler device is typically linked to the input of the gas chromatograph by a needle brazed or otherwise connected to the output tubing of the auto-sampler. The needle is then inserted through a hole bored in the septum nut to pierce a septum at the input of the gas chromatograph, and sample is then transferred from the auto-sampler to the gas chromatograph.
Unfortunately, this arrangement suffers from several disadvantages. First, the needle is not fixed in position relative to the septum nut. As a result, the needle can be accidently pulled from the gas chromatograph, with loss of sample to the air. Second, because the needle is not supported at the septum, the downward force exerted by the weight of the needle tends to increase the size of the hole at the septum, allowing sample to leak back through the septum hole into the air. Third, in certain applications the output line from the auto-sampler is capillary tubing having very narrow diameters, in the range of 0.32 millimeter to 0.53 millimeter. This tubing is utilized where very small amounts of sample are available for analysis. Capillary tubing is very fragile and is susceptible to damage if not adequately supported.